The resident who tested positive is under the age of 65.
RELATED: Get vaccinated to avoid flu and COVID-19 'double whammy', doctors say
Health officials have been warning the public of a "twindemic," urging everyone six months and older to get vaccinated as soon as possible.
"With the likelihood of both COVID-19 and seasonal flu activity this winter, contracting either disease may weaken your immune system and make you more susceptible to the other disease," said Solano County Health Officer Dr. Bela T. Matyas.
"Getting a flu vaccine this year is more important than ever, and flu vaccines are the best way to protect yourself, your family, and the community from becoming seriously ill with the flu. Vaccination not only reduces the risk of catching the flu, it also reduces the chance that you'll be hospitalized. In other words, the flu vaccine will provide some protection and reduce your chances of needing to be hospitalized if you do get sick," Dr. Matyas added.
RELATED: CA medical experts urge people to get flu shot to avoid 'twindemic' of COVID-19, influenza
Dr. Matyas says flu and COVID-19 symptoms can be very similar, but are different viruses. "It is important to note that flu is not COVID-19, which is caused by a different virus, and that the flu is not the same as the common cold, which is also caused by different viruses," she said.
Health officials say those with flu symptoms may be required a COVID-19 test and need to self-isolate while awaiting results.
For more information about influenza, visit the Centers for Disease Control and Prevention's website here.
For more news coverage on the coronavirus and COVID-19 go to ABC30.com/coronavirus